Solid-state storage subsystems execute many internal commands in the course of their normal operation. For example, garbage collection is frequently performed on memory blocks that may contain both valid and invalid data. When such a memory block is selected for garbage collection, the garbage collection operation copies valid data within the memory block to a new location in memory and then erases the entire memory block, making the entire block available for future data writes. In addition to garbage collection operations, solid-state storage subsystems also perform read and write operations as dictated by memory commands issued by host systems.